Aggression and the automobile have had a long standing association, yet research on aggressive behavior has neglected the roadway context. This chapter reviews existing work which has included archival analysis, field interview studies, personality research, and field experiments. Among the recurrent themes have been the relationship between aggressivity in driving to accident liability and to violence in the larger social context. Validity issues in road aggression research are discussed, and a typology of roadway aggression is presented. The typology maps a range of contemporary forms, most of which have never been investigated scientifically and have received sparse academic attention otherwise, despite having high social and scientific relevance. Disinhibiting influences that heighten the probability of roadway aggression are discussed